PROJECT SUMMARY/ABSTRACT Striking racial disparities in lung cancer are well-documented, with African Americans bearing a greater burden of lung cancer than other U.S. racial/ethnic groups. While smoking is a key established risk factor, biologic susceptibility and other health determinants influence lung cancer risk. Population-based studies in African Americans to understand risk factors for lung cancer have been limited and as a result little is known about the mechanisms that cause racial disparities in lung cancer. We hypothesize racial disparities in lung cancer incidence are multifaceted and a function of the interplay between biologic vulnerability and multilevel health determinants. To address gaps in knowledge of the complex mechanisms of racial disparities in lung cancer incidence, we propose to assess biologic vulnerability and the multilevel etiology of lung cancer incidence with the following specific aims: 1) identify novel genes and biologic pathways which may underlie racial disparities in lung cancer incidence and 2) quantify and build a profile of determinants (genetics, behavioral, social, and environmental) contributing to racial disparities in lung cancer incidence. We propose a case-control study of lung cancer (~5,300 lung cancer cases and ~8,100 controls, slightly over half African American) recruited from four geographic regions across the U.S. Our design first focuses on new pioneering predicted gene expression approaches, functional interpretation via bioinformatics annotation, and robust functional validation in an independent population to identify regulatory biologic mechanisms involved in lung cancer incidence and translate genetic findings into an interpretable biologic context. Our project then examines how neighborhoods, which can structure racial disparities geographically, (e.g., residential segregation) along with individual-level behavioral, health, and social determinants (e.g., smoking, pulmonary disease, socioeconomic status) can influence biologic pathways to lead to racial disparities in lung cancer incidence. This project is relevant to the mission of the National Institute of Minority Health and Health Disparities since it examines the contribution of multi-level factors driving racial disparities in lung cancer incidence among a health disparity population (African Americans). Our project fosters innovative collaborations among a multidisciplinary team with extensive expertise in racial disparities, lung cancer epidemiology, social determinants of health, biostatistics, cell biology, human genetics, and bioinformatics. A key innovative aspect of this proposal is its partnership with a Community Advisory Board to move empirical findings into recommendations for lung cancer prevention. Findings from our multidisciplinary approach will have sustained impact since it will reveal biologic pathways for precision medicine opportunities and motivate improved preventive strategies for risk and disparities reductions.